WO2006136498A1 - Installation for producing sterile bottles by blow molding sterilized preforms - Google Patents

Abstract

The invention relates to an installation for producing sterile bottles by blow molding preforms (12), which comprises a sterilizing treatment unit (26), a thermal conditioning unit, a molding unit, the sterilizing treatment unit (26) comprising an atomizing device (36) provided with a nozzle (38) that sprays, onto each preform (12), a flow (F) of vaporized sterilizing product inside the preform (12) in the form of a laminar flow and along a mean axis of spraying (A2) of the nozzle (38) which is, over-all, parallel to the axis (A1) of the preform (12) during treatment and which is radially off-center with regard to the axis (A1) of the preform (12).

Description

"Plant producing sterile bottles by blowing from sterilized preforms"

The invention relates to an installation producing sterile bottles by blow molding from plastic preforms.

The invention relates more particularly to an installation producing sterile bottles by blowing from plastic preforms, of the type in which the preforms are conveyed inside the installation in a continuous flow which flows from the upstream to the downstream, and of the type comprising:

a sterilizing treatment unit comprising a misting device provided with at least one nozzle which projects, towards the neck of each preform being treated, a stream of sterilizing product, in the form of a steam jet, with a view to sterilize at least the inner walls of the preform,

a thermal conditioning unit comprising at least one oven that heats the preforms,

- A molding unit comprising at least one mold and at least one blowing device which subjects each preform to an internal overpressure so that it takes the form of the cavity of the mold which produces a bottle.

Document US-A-2001/0010145 describes an example of an installation of this type intended to produce sterile bottles by blowing from sterilized preforms. This type of installation has the disadvantage of requiring a flow of sterilizing product and / or injection pressure of the sterilant product of significant values to succeed in completely covering the inner walls of the preforms so as to completely sterilize the inside of the preforms. . Therefore, the consumption of the sterilant product installation is therefore important and the sterilization operation expensive. Such a type of installation is more particularly described and shown in WO-A2-99 / 03667 which relates to a method and an installation for the manufacture of sterile plastic containers. The installation comprises a device for feeding preforms to heating means upstream of which the preforms are processed, at least inside the preforms, by sterilization means. The sterilization means comprise in particular a sterilization product, such as a chemical solution of hydrogen peroxide (H ₂ O ₂ ) that can be activated thermally, in particular by the heat of the heating means.

The sterilization means comprise, for this purpose, a spray consisting of a spray gun that allows the preforms to be wetted with "cold" sterilization product, that is to say having not been previously heated and found in the liquid state.

Then, the sterilization product will, under the effect of heat, be activated before evaporating. In the installation described in this document, the gun is typically a so-called bi-fluid type gun.

Indeed, the spray gun has a liquid nozzle and an air nozzle forming a circular projection assembly which is likely to be placed above the path of the preforms so as to spray a mist of sterilization product.

The mist of sterilization product is formed of a cloud of droplets which is projected by the spray gun into the interior of the preform in a turbulent type flow.

By definition, a flow is said to be "turbulent" when the Reynolds number R is, for example, greater than the critical Reynolds number Rc = 2000 and, conversely, is called "laminar". when the Reynolds number R is approximately less than the Reynolds critical number Rc = 2000.

It will be recalled that the Reynolds number R is defined by the formula: R = Ux / v in which "U" corresponds to the average flow velocity, "x" a linear reference dimension - such as the diameter "d" by example - and "v" at the kinematic viscosity coefficient of the fluid which is equal to the quotient of the viscosity coefficient by the specific mass of the fluid. It has been found that such a turbulent flow of sterilizing or sterilizing product inside the preform results in the formation of a set of droplets which are not homogeneously distributed on the inner wall of the preform.

Indeed, the use of a spray gun is characterized in particular by a large flow of sterilizing product which is obtained by compressing a gas, such as compressed air at pressures of about 2 to 3 bar, so it produces a turbulent flow.

However, the turbulent flow leads to inhomogeneous deposition of residual droplets of sterilizing product on the inner walls of the preforms. In addition, the droplets of sterilant product form a surplus that is not fully vaporized during heating.

These droplets of sterilizing product thus cause, on the one hand, a chemical attack of the preform material, generally made of polyethylene terephthalate (PET), and, on the other hand, during the heating of the preforms, produce a magnifying effect on the thermal radiation. of heating, which causes the appearance of spots on the walls of the bottles from the preforms concerned.

The appearance of such spots on the walls of bottles, is a lack of appearance of the product, which is still sometimes called "orange peel appearance". The present invention aims in particular to remedy these drawbacks, more particularly to make it possible to obtain the desired degree of sterility at least over the entire inner wall and the neck of the preform and to produce bottles which are free from defects in appearance such as "Orange peel".

For this purpose, the invention proposes an installation of the type described above, characterized in that the mean axis of projection of the nozzle is generally parallel to the axis of the preform being processed and eccentric radially, relative to the preform axis and in that the flow of sterilant product is projected inside the preform in the form of a flow of laminar type.

By projecting the flow of sterilizing product in the form of a laminar flow, for example from a hot mixture of product vapor such as hydrogen peroxide (H2O2) and air, there is obtained a homogeneous distribution of the sterilizing product on the inner wall of the preform thus eliminating the risk of appearance appearance defects of the "orange peel" type. However, according to the profile of the inner walls of each preform, it is not possible with a flow of laminar type to reach in a certain way the bottom of the preforms.

Indeed, since it projects a laminar flow of sterilizing product in a preform, in particular of small diameter and great length, it is created by the very fact of this type of flow a stagnant air plug, called overpressure, in the bottom of the preform which disrupts the uniform condensation of the sterilant product.

Due to the offset E of the nozzle projection axis relative to the axis of the preform, the laminar flow of sterilizing product condenses uniformly over the entire inner wall of the preform, including the bottom. The problem of forming such an overpressure plug is thus advantageously solved and all of the inner wall of the preform and the neck are perfectly sterilized by the laminar flow of sterilizing product. According to other features of the invention:

the projection axis is eccentric at least nineteen percent of the value of the inside diameter of the opening defined by the neck;

- the projection axis is eccentric at a maximum of thirty-two percent of the value of the inside diameter of the opening defined by the neck;

in the sterilizing treatment unit, the preforms are generally aligned in a longitudinal direction of travel, and are arranged in the upright position, parallel to one another, and the nozzle projection axis is radially offset in a substantially orthogonal direction, relative to the direction of travel;

the nozzle produces a flow of sterilizing product generally in the form of a vertical curtain; the misting device is provided with a plurality of nozzles which are generally aligned longitudinally, and the axes of projection of the nozzles are substantially parallel;

the sterilizing product consists of a compound containing hydrogen peroxide or vaporized hydrogen peroxide which is activated by heating above an activation temperature;

the hydrogen peroxide is activated by heating inside the oven of the thermal conditioning unit by heating the preform to a temperature greater than the activation temperature;

the hydrogen peroxide is activated in the sterilizing treatment treatment unit by spraying on the previously heated preform at a temperature above the activation temperature;

- Hydrogen peroxide is projected at a temperature greater than one hundred and six degrees Celsius, for example a temperature close to one hundred and ten to one hundred and twenty degrees Celsius.

Other features and advantages of the invention will appear on reading the detailed description which follows for the understanding of which reference will be made to the appended drawings in which: FIG. 1 is a diagram which represents a first example of implementation in an installation producing bottles by blowing and comprising a sterilization unit according to the teachings of the invention;

- Figure 2 is an axial sectional view along the section plane 2-2 which schematically shows a preform in the sterilization unit of the installation of Figure 3;

- Figure 3 is a top view which shows a series of preforms in the sterilization unit;

- Figure 4 is a diagram which shows a second example of implementation in an installation producing bottles by blowing and comprising a sterilization unit according to the teachings of the invention.

In the remainder of the description, similar or identical elements will be designated by the same references. In Figure 1, there is shown a plant 10 producing bottles 14 by blowing from preforms 12 of plastic.

This type of installation 10 is used, for example, for the manufacture of plastic bottles 14 such as polyethylene terephthalate (PET).

Each preform 12 has the overall shape of a tube which is closed at one end and whose other end already has the final shape of the neck 16 of the bottle 14. In Figure 2, a preform 12 is shown, without limitation, with the axis A1 of its cylindrical body 18 which extends vertically.

The axis A1 of the body 18 coincides with the axis of the neck 16. The lower end 20 of the preform 12 is closed, while its upper end forms the neck 16 which defines an opening 22 and which is provided here with an external radial collar 24.

The preforms 12 are here made beforehand, according to an injection molding process.

The preforms 12 are conveyed inside the installation 10 in a continuous flow that flows from upstream to downstream, that is to say from left to right, considering FIG. In the first example shown in FIG. 1, the plant 10 comprises, from upstream to downstream, a unit 26, called a sterilizing treatment unit, preferably comprising means for preparing the sterilizing product, a thermal conditioning unit. 28, and a molding unit 30. Advantageously, the installation 10 also comprises, after the molding unit 30, a filling unit 32 and a closure unit 34.

The sterilizing treatment unit 26 comprises a misting device 36 provided with at least one nozzle 38 which projects, towards the neck 16 of each preform 12 during treatment, a flow F of sterilizing product so as to produce bottles

14 that are sanitized or sterile depending on the application.

The sterilizing treatment unit 26 will be described in more detail below, in connection with the features of the invention.

The thermal conditioning unit 28 comprises at least one oven 40 which heats the preforms 12 to a temperature suitable for molding. The molding unit 30 comprises at least one mold 42 and at least one blowing device 44 which subjects each preform 12 to an internal overpressure so that it takes the form of the impression of the mold 42, which produces a bottle 14 .

The molding unit 30 may also comprise elongation means (not shown) which stretch the preform 12 towards the bottom of the mold 42, during the molding operation.

The filling unit 32 injects the product 46 to be packaged in the bottles 14 coming from the molding unit

30, then the closure unit 34 hermetically closes the sterile bottles 14 filled for example with a suitable capsule 48, alternatively a cap and / or a cap.

We will now describe, in more detail, a preferred embodiment of the sterilizing treatment unit 26 according to the invention.

Preferably, the sterilizing product consists of a compound containing hydrogen peroxide or vaporized hydrogen peroxide (H ₂ O ₂ ) which is projected towards the preforms 12 in the form of a jet of gas containing product sterilizing in the vapor state, advantageously a jet of dry steam.

For this purpose, the means (not shown) for preparing the sterilizing product of the sterilizing treatment unit 26 comprise in particular heating means (not shown) of the sterilizing product and a source of air (not shown), advantageously compressed and or sterilized by any suitable means, which is intended to propel the sterilant through the nozzle 38 of the misting device 36.

The compressed air is advantageously dehydrated and circulates at low speed in a directional flow so as to constitute a vector for the sterilant product vapor.

The concentration of steam sterilizing product is, for example, substantially equal to twenty-five percent. At the outlet of the nozzle 38, the vapor containing the sterilant product reaches a given temperature T substantially greater than the evaporation temperature of the sterilant product.

In the case of using hydrogen peroxide (H ₂ O ₂ ), the temperature T at the outlet of the nozzle is advantageously greater than one hundred and six degrees Celsius (106 ^° C.), preferably between one hundred and ten degrees Celsius (1 1 O). ⁰ C) and one hundred and twenty degrees Celsius

(12O ⁰ C).

When this steam comes into contact with the inner walls 50 of the preforms 12, which are colder, the sterilizing product condenses in the form of mist so that a film of sterilizing product is deposited on the whole of the preform 12, in particular on the inner walls 50 of the preforms 12 which thus fog up with a sterilizing product film. Advantageously, the sterile product is deposited by condensation in a substantially uniform film that allows, compared to the state of the art, to eliminate any risk of appearance of spots and appearance "orange peel".

The preforms 12 then pass into the thermal conditioning unit 28 comprising the heating oven 40 for heating the preforms 12 to a temperature greater than or equal to the molding temperature in order to then perform the blowing operation.

Of course, the molding temperature depends on the type of preform 12 which is a function of the applications, for example the temperature is for example between ninety-five degrees Celsius (95 ^° C) and one hundred thirty-five degrees Celsius

(135 ^° C.)

However, the sterilization is obtained by carrying the preform 12 covered with sterilizing product mist film beyond a temperature, called activation temperature.

The activation temperature of hydrogen peroxide (H ₂ O ₂ ) is for example from about seventy degrees Celsius (70 ^° C.), that is to say a temperature below the molding temperature.

Advantageously, the passage of the preforms 12 in the thermal conditioning unit 28 thus causes the activation of the sterilizing product by heating, which has an immediate bactericidal effect on the inner walls 50 of the preforms 12.

In known manner (not shown), such a preform heating furnace 40 comprises a longitudinal heating tunnel along which the preforms 12 are transported by a transport device between a first end of the tunnel where the preforms 12 generally penetrate cold before exit through the second end of the tunnel heated or reheated, ready for the blowing operation.

To ensure the heating of a preform 12 in depth, that is to say both of the bottom end 20 forming the bottom of the cylindrical wall of the body 18, the preforms 12 are generally rotated on themselves during their circulation in the oven 40 by means of a transport device comprising gripping means for example of the type described in WO-A-00/48819.

In addition, one wall of the tunnel is equipped with radiation heating means while the other wall is provided with ventilation holes to allow the passage of blown air to promote uniform heating throughout the thickness of the preform 12 without overheating the layer of surface material.

In fact, the blown air makes it possible to evacuate the convection heat caused by the heating means to promote the penetration of the radiation that they produce into the thickness of the material constituting the preform 12. For more details on such heating furnaces 40 of preforms, reference will be made for example to EP-A-0.620.099 or EP-A-0.564.354. However, in the case of an installation 10 as represented in FIG. 1, the air blown onto the preforms 12 in the oven 40 causes the removal of all or part of the sterile product mist film previously deposited on the outside. of the preform 12 by condensation in the sterile treatment unit 26.

Thus, at the outlet of the furnace 40, preforms 12 are obtained which are mainly sterile inside.

By means of an installation 10 according to the first example of implementation, a logarithmic reduction in the number of seeds of the order of 3D is obtained, or else 3 Log equivalent to 1000 units (10 ³ ).

In known manner, the amount of seeds is for example counted by counting after washing, filtration and culture operations. Advantageously, the oven 40 includes protection means, in particular for limiting the corrosion of the parts or parts exposed to the sterile product thus blown inside the tunnel.

According to an alternative embodiment (not shown) of the installation 10, a sterile containment chamber may be provided to allow treatment of preforms 12 and bottles 14 completely aseptic.

According to the embodiment represented here, in particular in FIG. 3, the preforms 12 run in the sterilizing treatment unit 26 while being aligned, in a vertical position, in a longitudinal horizontal direction, called the X1 direction of travel, the collar 16 towards the the top.

The X1 direction of travel passes through the A1 axes of the preforms 12 being processed. According to the teachings of the invention, the average axis A2 of projection of the nozzle 38 is generally parallel to the axis A1 of each preform 12 being processed and it (A2) is eccentric radially, with respect to the axis A1 of the preform 12, a determined offset value E and the flow F sterilant product is projected inside the preform 12 in the form of a flow of laminar type.

Preferably, the axis A2 projection, which is here vertical, is eccentric along an inner radius R1 of the neck 16 which is orthogonal to the direction X1 scroll.

As a variant, the vertical axis A2 of projection is eccentric along an inner radius R of the neck 16 which is parallel to the longitudinal direction X1 of travel or which forms with said longitudinal direction X1 of travel an angle θ of determined value.

Advantageously, the shape of the nozzle 38 makes it possible to project, downwards, a flow F of sterilizing product generally in the form of a laminar flow, that is to say here in the form of a vertical curtain and of longitudinal preference.

For this purpose the nozzle 38 advantageously comprises a longitudinal or circular slot, alternatively, for example, a generally circular hole for projecting the flow F.

The laminar flow F here extends generally along a longitudinal vertical plane, said projection plane X2, which is radially offset, with respect to the direction X1 of travel, by a distance equal to the offset E.

The flow F sterilizing product here admits an infinity of axes A2 projection means that extend vertically in the projection plane X2.

Preferably, the offset value E is between a minimum value Emin substantially equal to nineteen percent of the inside diameter D1 of the neck 16 of each preform.

12 and a maximum value Emax substantially equal to thirty-two percent of the inside diameter D1 of the neck 16.

According to an advantageous embodiment, the offset value E is chosen fixed and substantially equal to eight millimeters, so that it is suitable for preform models 12 having inner diameters D1 of between about twenty-five and forty-two millimeters.

Thanks to the arrangement of the nozzle 38 according to the invention, the flow F of the sterilizing product is substantially flush with a first sector 52 of the inner wall 50 of each preform

12, so that the flow F sterilizing product licks said sector

52 of the inner wall 50.

Arriving at the lower end 20 of the preform 12, the flow F of sterilizing product slides on the bottom of the preform 12 and goes up along a second sector 54 of internal wall 50, diametrically opposite the first 52.

Thus, the flow F sterilizing product generally sweeps the entire inner wall 50 of each preform 12, according to a flow of laminar type. The arrangement according to the invention makes it possible in particular to prevent the creation of an overpressure plug, in the bottom of the preforms 12, which would prevent the sterilizing product from reaching the bottom.

In particular, the speed of propulsion of the sterilizing product, at the outlet of the nozzle 38, is sufficiently low to obtain a flow of laminar type, for example of the order of 0.3 to 0.5 m / s with a nozzle of a length of about 35 mm and calibrated diameter of about 3 mm.

It is noted that the flow F of the sterilizing product creates a sterilizing product mist that diffuses around the flow F, which allows the sterilizing product to be deposited in particular on the entire inner wall 50 of each preform 12.

In addition, this fog is also deposited on the outer wall of the neck 16, which makes it possible simultaneously to sanitize or sterilize the inner wall 50 and the neck 16 of each preform 12.

FIG. 4 represents a second example of implementation of the invention in a plant 10 'producing sterile blow bottles which, similar to that of Figure 1, will be described below by comparison.

The installation 10 'according to FIG. 4 differs essentially by the inversion effected between the thermal conditioning unit 28 and the sterilizing treatment unit 26.

Thus, the installation 10 'comprises, respectively from upstream to downstream, a thermal conditioning unit 28, a sterilizing treatment unit 26 and a molding unit 30.

The units 26, 28 and 30 are here analogous to those of FIG.

The preforms 12 are therefore first heated by the thermal conditioning unit 28 so as to be brought to a temperature greater than or equal to the molding temperature, for example between ninety-five degrees Celsius (95 ^° C) and one hundred thirty five degrees Celsius (135 ⁰ C).

Then preforms 12 and heated pass through the sterilizing treatment unit 26 to be sterilized.

However, since the preforms 12 are at a temperature greater than the activation temperature, for example of the order of about seventy degrees Celsius (70 ^° C.) for hydrogen peroxide (H ₂ O ₂ ), it does not condensation does not occur as before and thus deposition of a uniform film of sterilizing product mist.

Indeed, the sterilizing product is instantly activated and evaporates in contact with the heated preform 12, thereby producing a similar bactericidal effect on the whole of the preform 12, that is to say both on the inner wall 50 only on the outer parts of the preform 12.

Thanks to the installation 10 'according to FIG. 4, the preforms 12 are thus completely sterilized and sterilization degrees of the order of 6 Log are obtained, that is to say higher than those obtained with the installation 10 of Figure 1. Advantageously, the oven 40 of the thermal conditioning unit 28 is a conventional oven which, upstream of the sterilizing treatment unit, is not as previously exposed to risks of corrosion by the sterilizing product and does not require therefore no special additional means of protection.

The preforms 12 traversing the installation 10 or 10 ', in particular the sterilizing treatment unit 26, are here oriented vertically with the neck 16 upwards, that is to say in the so-called "neck up" position.

Alternatively, the preforms 12 are vertically oriented the sterilizing treatment unit 26 with the neck 16 downwards, or

"neck down", the preforms 12 being capable of changing vertical orientation within the installation 10, 10 ', in particular from one unit to another.

The invention has been described with a misting device 36 advantageously comprising a nozzle 38 in the form of a longitudinal or circular slot. Of course, according to alternative embodiments (not shown), the flow F sterilant product can be achieved by a plurality of tubular nozzles 38 aligned in the projection plane X2.

It is noted that the installations 10 and 10 'have been shown with aligned processing units 26, 28, 30, 32, 34, but these processing units can be arranged in a different configuration.

Some processing units 26, 28, 30, 32, 34 may implement rotating devices such as carousels (not shown).

Claims

1. Apparatus (10, 10 ') producing sterile blow-off bottles (14) from plastic preforms (12) of the type in which the preforms (12) are conveyed within the installation (10, 10) ') in a continuous flow that flows from upstream to downstream, and of the type comprising: - a sterilizing treatment unit (26) comprising a misting device (36) provided with at least one nozzle (38) which projects, to the neck (16) of each preform (12) during treatment, a flow ( F) sterilizing product, in the form of a jet, for sterilizing at least the inner walls (50) of the preform (12), a thermal conditioning unit (28) comprising at least one furnace (40) which heats the preforms (12), - a molding unit (30) comprising at least one mold (42) and at least one blowing device (44) which subjects each preform (12) to an internal overpressure so that it takes the form of the mold cavity (42) to produce a bottle (14), characterized in that the axis (A2) for projecting the nozzle (38) is generally parallel to the axis (A1) of the preform (12) being processed and eccentrically radially, with respect to the axis ( A1) of the preform (12) and in that the flow (F) of sterilant product is projected inside the preform (12) in the form of a flow of laminar type. 2. Installation (10, 10 ') according to claim 1, characterized in that the projection axis (A2) is eccentric at least nineteen percent of the value of the inside diameter (D1) of the opening ( 22) delimited by the neck (16). 3. Installation (10, 10 ') according to one of claims 1 or 2, characterized in that the axis (A2) projection is eccentric at most thirty-two percent of the value of the inner diameter (D1) of the opening (22) defined by the neck (16). 4. Installation (10, 10 ') according to any one of the preceding claims, characterized in that, in the sterilizing treatment unit (26), the preforms (12) are generally aligned in a longitudinal direction (X1) of scroll, and are arranged in a standing position, parallel to each other, and in that the axis (A2) of projection of the nozzle (38) is offset radially in a substantially orthogonal direction, with respect to the direction ( X1) scrolling. 5. Installation (10, 10 ') according to the preceding claim, characterized in that the nozzle (38) produces a flow (F) sterilizing product generally shaped vertical curtain. 6. Installation (10, 10 ') according to one of claims 4 or 5, characterized in that the misting device (36) is provided with a plurality of nozzles (38) which are generally aligned longitudinally, and in that the axes (A2) projection of the nozzles (38) are substantially parallel. 7. Installation (10, 10 ') according to any one of the preceding claims, characterized in that the sterilizing product consists of a compound containing hydrogen peroxide or vaporized hydrogen peroxide which is activated by heating at beyond an activation temperature. 8. Installation (10) according to claim 7, characterized in that the hydrogen peroxide is activated by heating inside the oven (40) of the thermal conditioning unit (28) by heating the preform (12). ) at a temperature above the activation temperature. 9. Installation (10 ') according to claim 7, characterized in that the hydrogen peroxide is activated in the sterilizing treatment treatment unit (26) by spraying on the preform (12) previously heated to a temperature greater than the activation temperature. 10. Installation (10, 10 ') according to one of claims 7 or 9, characterized in that the hydrogen peroxide is projected at a temperature greater than one hundred and six degrees Celsius.